4 BULLETIN 137, U. S. DEPARTMENT OF AGRICULTURE. 



along the same line and because, in many instances, this investiga- 

 tion has merely attempted to discover whether results obtained by 

 them were sustained under the great variations of the American cli- 

 mate. In barley the greatest achievement at Svalof was the dis- 

 covery of two kernel characters, which, by various combinations, 

 gave four separations under each previous group. 



These investigators found, that the rachilla in some barleys was 

 covered with long straight hairs and in others with short curly ones; 

 also that the inner pair of dorsal nerves sometimes bore teeth and 

 were sometimes smooth. The stability of these characters was ques- 

 tioned by Broili (10), who claimed to have frequently observed one 

 form in the progeny of another. Tschermak (13), Blaringhem (7), 

 and others have supported the investigators of the Plant-Breeding 

 Association at Svalof, at least so far as the basal bristle is concerned. 

 Although none are to be compared with this discovery in importance, 

 many other studies have been made at Svalof. At one time they had 

 developed a very elaborate s}^stem of measurements made by means 

 of many ingenious mechanical devices. They have, unfortunately, 

 made no specific, comprehensive publication of their negative re- 

 sults, but according to Newman (20) and others they have aban- 

 doned the use of many of the measurements that were formerly 

 made. Of those retained, the most important from the standpoint 

 of this paper is that of density. In the early history of the asso- 

 ciation two or three varieties were obtained by the "elite" method. 

 They chose an arbitrary density and made mass selections of spikes 

 conforming to that measurement. Later, they used density as a 

 means of valuing head measurements, as a long head if loose might 

 contain no more grains than a short one if compact. They finally 

 employed it in varietal description. Blaringhem (7), who has fol- 

 lowed the work of the Svalof association quite closely, used density 

 as an indication of purity and to reveal the effect of climate. 



The morphological characters of the seed coat and the kernel have 

 been treated by Kudelka (16) and Johannsen (14), but there is no 

 suggestion of usable varietal differences. 



The composition of the grain has been studied by a few American 

 and a large number of European scientists. Le Clerc and Wahl 

 (17), who have made the most comprehensive of the American 

 studies, have clearly demonstrated that composition is of slight use 

 as a varietal character for, while there are differences, the effect of 

 location and season is many times greater than that of variety. 



Color in barley has been employed by all systematists, but has 

 received very little analytical attention. Brown (11) has a note on 

 the color in the variety coerulescens, and numerous authors have dis- 

 cussed the occurrence of pigments in other plants. A recent article 

 by Wheldale (26) treats of the chemical nature of anthocyanin and 

 traces its origin from a glucosid. 



